tailieunhanh - Nonlinear Microwave Circuit Design phần 8

đúng cách và khác nhau tải nội dung hài hòa của sản lượng hiện tại, như trong F-Class hay Class ngược-F phương pháp tiếp cận [4-10], hoặc một thiết kế cẩn thận của mạng lưới đầu ra, cả hai gộp hoặc theo hình thức phân phối, trong khi sử dụng các thiết bị hoạt động như một công tắc tinh khiết, | 268 OSCILLATORS analysis of the oscillator circuit linearised at the bias point without the probe. Then the probe is introduced injecting a probing signal with a frequency equal to the linear approximation and with a small amplitude. This situation corresponds to the initial oscillation startup when the oscillation is still growing in time because the power generation at RF by the negative resistance or conductance of the active device prevails on the power dissipation on the positive resistance or conductance of the passive elements including the load. The control quantity is not zero as the oscillator delivers power to the probing generator. Then the amplitude of the probing signal is stepped up until the amplitude of the oscillation brings the active device into saturation reducing thus the value of the power-generating negative resistance or conductance see Section . The value of the control quantity will approach zero for a given value of the amplitude of the probing signal it will not probably be exactly zero because the oscillation frequency usually shifts in large-signal regime with respect to the small-signal linear calculation. However this is a good starting point for the self-consistent simultaneous solution of eq. and avoiding the degenerate solution. It must be pointed out that a quasi-linear determination of the start-up frequency can alternatively be obtained by performing repeated non-autonomous analyses with a small amplitude of the probing signal and fixed frequency the frequency value is swept within a suitable range as said above. The frequency at which the control quantity has zero imaginary part and negative real part is a suitable candidate for oscillation startup and a good first guess of the large-signal oscillation frequency. This method is easily modified to automatically avoid the degenerate solution in the same way as described in eq. above. Instead of eq. the Kurokawa condition can be written for the .